Diffusion MRI of Complex White Matter and Connectivity

该项目研究了磁共振成像扩散谱成像或DSI的新方法的能力，以映射复杂的白色物质结构和人脑中的神经连接。 这种能力最终可能使非侵入性地定义大脑的线路图成为可能。 目前基于扩散张量磁共振成像（DTI）的方法使得获得显示每个位置白色物质平均方向的地图成为可能，包括我们自己在内的几个研究小组已经设计出将追踪程序应用于这些方向场的方法，以定义神经通路的大规模轨迹。 然而，这种方法有一个严重的基本限制，即它不能描述每个组织位置的多个方向。 我们最近描述的扩散光谱成像方法克服了这一点，首次提供了解析每个图像位置处的整个分布白色物质方向的能力。 这些地图提供了大脑白色物质束的解释和交叉的直接描述。因此，该项目将追求三个主要目标：一。优化脑白色物质体内成像的扩散光谱成像：ii.为了验证离体（通过与共聚焦显微镜的相关性）和体内（通过与患者轴突变性的相关性）复杂白色物质结构的扩散光谱成像，和三.通过与人类视觉系统中功能性磁共振成像（fMRI）定义的已知神经通路相关，测量大规模白色物质轨迹的DSI计算的准确性。

This project investigates the capacity of a new method of magnetic resonance imaging diffusion spectrum imaging or DSI, to map complex white matter architecture and the neural connectivity in the human brain. This capacity may make it possible ultimately to define the wiring diagram of the brain noninvasively. Current methodology based on diffusion tensor magnetic resonance imaging (DTI) makes it possible to obtain maps that show at each location the mean orientation of white matter, and several research groups including our own, have devised methods to apply tracing procedures to these orientation fields to define the large-scale trajectories of neural pathways. This approach, however, suffers a serious and basic limitation, namely, its inability to describe more than a single orientation at each tissue location. Diffusion spectrum imaging methodology we have recently described overcomes this, providing for the first time an ability to resolve entire distributions white matter orientations at each image location. These maps provide direct descriptions of the interpretation and intersection of cerebral white matter tracts. Accordingly, this project will pursue 3 principal aims: i. To optimize diffusion spectrum imaging for in vivo imaging of cerebral white matter: ii. To validate diffusion spectrum imaging of complex white matter architecture ex vivo (by correlation with confocal microscopy) and in vivo (by correlation with axonal degeneration in patients.), and iii. To measure the accuracy of DSI computation of large scale white matter trajectories, by correlation with known neural pathways defined by functional magnetic resonance imaging (fMRI) in the human visual system.